The Oklahoma Colony of Canine Hemophilia was established at the College of Veterinary Medicine, Oklahoma State University, to provide healthy animals (beagles) to be used as an experimental model for the human disease. Collaborative research projects with local investigators at the College of Veterinary Medicine and the University of Oklahoma Health Sciences Center have provided an opportunity to perform unique experiments which cannot be performed on humans. The continued collaboration between the Principal Investigator of this proposal and investigators at the Oklahoma Medical Research Foundation Hematology Research Laboratories combines the animal resource with a specific research proposal to define the role of the lymphocyte in this disease. Approximately 40 beagles will be maintained with homozygotes and heterozygous Factor VIII deficiency as well as a few animals with Factor VII and Factor IX deficiency which can be utilized later in the research on the site of synthesis of Factor VIII. The use of human and canine material in the investigation of this study will be a collaborative effort for investigators on both campuses.